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Would a drone strike be more dangerous than a bird strike?
Let's say you have a seagull and a drone of a comparable size.  Pretend either one was going to be ingested by large turbo fan engine, like the one found on a 737 (eg., the CFM-56)
Which would cause more damage and why?  I'm particularly interested in how the fan blades and compressor stages will be affected by the difference in materials.

Related: Can a drone hitting a plane be mistaken for a birdstrike?

@fooot Agreed.  This question is kind of a focused continuation of that question.

Interestingly, I found a news report just yesterday saying a statistics-based study had indicated drones were very unlikely to be a hazard. I was sceptical and did a bit of searching and found an older paper saying the exact opposite, based on more mechanical arguments. I suspect the answer might be, we don't know until someone tests a few engines...

@Andy Given the numbers of birds out there compared to the numbers of drones, you're odds are probably far higher of taking damage from a bird. The stats out there for annual costs of bird-strikes are some prett big dollar (Euro) amounts, while for drones, the stats are pretty minute. But, if you get one bird in "this" engine, then one drone in "that" engine, of equal size & weight, the mechanical effects will take over, and that's where I suspect that the drone will really tear things up far worse than the bird flesh will.

@RalphJ agree with your argument about the sheer numbers of birds. As for mechanical aspects of drones, I searched and wasn't able to find anyone doing actual tests yet, which is disappointing considering engines have been deliberately used for bird tests in the past. (Some are doing computer simulations.) Hopefully tests will happen eventually.

The "drone swarm" from this question might do some damage?

Not a test but there has at least been a study.

@Ralph J: OTOH, I doubt that birds intentionally fly close to jet airplanes, and would do their best to avoid them.  Can't say the same of everyone who flies drones, as witness this from today's news: http://abcnews.go.com/US/wireStory/drone-200-feet-airliner-la-airport-37769365 (3/18/2016)

This might be more interesting question with a propeller plane. My personal record was 39 Canadian geese removed by ground crew from a runway after a flock warming themselves decided to take off into my path (Not counting those that did not land on the runway). There was no damage to the A/C. I have to wonder if the mixmaster out front would have done the same on a drone.

While I have done significant research related to UAS bird impact UAS Safety report I have not been able to find specific data related to this particular import question. High speed impacts are a complex phenomena, and detailed data is necessary. If it were easy to characterize them based on just a paper analysis, engine manufactures would not do actual bird, water and hail testing I have heard many claims about "soft" versus "hard", but anyone who has done a belly-flop from a h

While it's true you will never really have the details until a full study is done, you can do material simulations that will give you a pretty good idea of what may happen.  It's somewhat like the design of modern aircraft, you do most of the early design work and testing on a computer in a simulation.  But eventually you will need to build a physical model and go to a wind tunnel to verify the computer model.  Anyway, I'm not even looking for a computer simulation, I'd just take some rough figures if they are to be had.  Beginning to doubt they are.

There is a numerical study on the topic at VirginiaTech, where they simulated a 5kg drone being ingested by a turbofan, some pictures related to the study below:

On the same  Aerospace America Article it can be read that:

FAA will begin testing of drone ingestion next year
The metric for danger is the density of the material, so metallic parts are more critical than the bird bones/tissues. Modern drones have more aluminum parts, but the most critical component of a Drone ingestion would be the batteries.

Comparing different sizes, a commercial quad copter is around 1.4kg, while the most frequent bird impact (from FAA database) is around 1.8kg.
This is not the worst case scenario since larger drones are commercially available, and a goose, which can weight up to 6kg.

Thanks for finding this. They have the article online too (though there isn't much more than the illustration shown). link

@Andy Thanks for the feedback, I included the link you provided into the answer to improve readability

Birds are soft; drones tend to have at least some parts that are hard metal.  If a small bird goes through the fan blades of an engine, it gets pretty cleanly sliced, and often causes no damage at all.  (A bigger bird going into the core is a different matter -- ask Captain Sullenberger!)  I'd suspect that the metallic parts in a drone would cause far more damage to the fan blades than the bird would -- not necessarily anything immediately catastrophic, but nicks in the leading edge of the fan blades would probably be visible when looking at the shut-down engine, and those take maintenance action to resolve.
Anything going into the core is more involved than if it went only into the fan blades, and the difference between bird flesh cooking and getting spit out versus the metal & plastic of the drone melting & causing clogs & damage is probably another point of difference -- the bird may cause damage, but the drone would probably be more likely to cause damage, and would probably cause greater damage.
To what extent the crew could tell the difference in flight, is hard to say.  (The experience with bird-strikes to the engines is pretty wide-spread, at least in terms of corporate knowledge; the number of drones-in-engines is far, far fewer.)  Knowing that something is wrong with a motor, and dealing with it, isn't the same as knowing the cause -- at least until you're back on the ground and the engine gets inspected.
UPDATE: This Popular Mechanics article discusses these sorts of issues, with some simulations linked, such as this video.

I think this is a good framework for an answer, but I really was hoping for more specific details into how the materials would interact with the internals of the engine...

This answer is mostly speculation - one could easily argue that birds are mostly sacks of water (like most organisms) and as such are made of a heavy, incompressible(!) medium that may cause bending and cracking rather than piercing or scratching damage. I think any answer not reporting on field tests (whether intentional or accidental) is indeed not very useful to @JayCarr as he indicates.

Take a meat cleaver and chop through a chicken 50 times. Inspect kinfe for damage. Now chop through 50 drones & inspect. Bet you find more nicks on the blade from metal in the drones. Until P&W or GE is willing to write off an engine or several by flying drones into them, we probably won't have perfectly comparable engineering data, but intuition informed by experience can tell us what the qualitative results are most likely to be. We DO know the damage that FOD does to motors, and pound-for-pound, birds do far less damage per incident than metal & rocks do.

@RalphJ Sanchises is suggesting that at the speeds involved, water doesn't work the way our low-speed intuition suggests, and I don't think a low-speed thought experiment is helpful. On the other hand your suggestion about FOD seems very relevant -- anything about aluminum or other lightweights in particular?

@Charles  There is ample experience with birds going through engines, and they tend to get neatly chopped up & spit out without significant damage to the engine (as long as they missed the core). We know from experience with FOD that metal -- any type -- is far, far worse on motors, even at low speeds. For somebody who doesn't think a fan blade will fare far worse trying to slice through metal than it does slicking through bird at the same speed, regardless of what that speed is, I don't have anything else I can offer for enlightenment.

While a collision with anything during flight would be bad, please keep the fear of drones in perspective.  the OP's scenario has never happened.
There have been more than a million hours of flight of small drones, yet there is not one verifiable report of a collision between a personal drone and a manned aircraft. Not one.
There is also not one verifiable report of a drone crash in the U.S. that resulted in a serious injury as defined by the NTSB to someone not connected to the flight. Not one. It is a safety rate that all other segments of aviation would be jealous to have.
The only significant metal in most consumer drones is the motors, about the size of a large hailstone.  The batteries feel dense, but they are mostly a liquid polymer electrolyte.
Yes, the FAA plans to include a drone in their engine ingesting tests next year.  The problem I see is which drone?  The333.org has examined 5469 Exemptions through 7/12/2016 and the data contains 902 Models of UAS from 256 manufacturers.  So, which one is "typical"?

The batteries come with a stainless steel container. THAT, and the mass inside, makes them more dangerous than birds in a collision.

The SS wrap is not much thicker than your kitchen aluminum foil, and not all batteries have that.  As I said, the batteries are mostly liquid.

Citations or sources? This may be right, but currently reads like opinion.

There are 10-30 billion birds in the US and so I'm not particularly impressed with a million hours of drone flights compared to a quadrillion hours of bird flight since the FAA was founded. 13,546 bird strikes were reported to the FAA in 2015; if only 20% are reported (Khan, Kapania & Johnson) we'd need more than ten billion hours of drone flight before we'd expect to see a single collision, if birds and drones flew similarly.


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What type of helicopter is this?

Wondering what kind of aircraft this is. Military or commercial? Photographed nearing island HK (possibly near Wanchai) an hour or two ago.

That looks like a Harbin Z15 (aka AC352, Eurocopter EC-175, Airbus H-175).
This model isn't used by any military but ones operated by the HK government use a military-like color

B-LVD (picture above) seem to have flown today.

Looks  like you nailed it.

BTW, the past tense of "fly" is "flew" or "have flown".  So "B-LVD seem to have flown today".  I apologize on behalf of the English language to anyone that has to learn it.

@PeterCordes Yeah I was a bit hesitant on that but too lazy to look it up. Now I know "flied" is specific to baseball. Thanks.

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DP confusion. Do I turn left or right if not told?
Please take a look at the MIA5 depatarture from KOPF:
MIA5 Page 1
MIA5 Page 2
The instructions seem in conflict. Specifically, suppose you are taking off RW 270R and want the WINCO transition.
The textual instructions are:

climb heading 273°, thence....
....maintain 2000 or higher altitude
and expect vectors to appropriate transition. Expect further
clearance to filed altitude 10 minutes after departure.

OK - that
    is straightforward essentially runway heading to vectors to WINCO.
However, there is a third text segment on page 2 regarding the WINCO transition:
"From over DHP VORTAC on DHP R-322 to WINCO INT"
DHP is a LEFT turn from OPF and would take the airplane directly across the KMIA departure / arrival paths; WINCO is a right turn. Which is it? What do I do in lost comm? Why do they have "from over DHP" I would expect the instruction to be "climb heading 273° to intercept DHP R-322 to WINCO"
Also, if I load that procedure into Garmin Pilot, it just shows a path direct from OPF to DHP then to WINCO which I know is wrong.

The ROUTING is DHP 322 radial to WINCO.  So that's the course line that you'd intercept when so instructed.  There is no reason to actually start at DHP, and since you'll be flying the heading off the runway, the leg from the field to DHP in the Garmin is immaterial.  You can expect that they'll either clear you to WINCO, or (for a non-RNAV aircraft, most likely)  that they'll clear you on a heading to intercept the DHP 322 radial to WINCO (and thence as filed), so you'd cycle the active leg from the {OPF to DHP} leg, to the next leg, which is {DHP to WINCO} (which is the same as the DHP 322 radial), and then you'd intercept that active leg.
Nothing in those instructions is telling you to fly to DHP, nor should you expect that you'd get a clearance to do so.
To answer the question in the title, until you're told otherwise, you fly the initial heading in the text instructions.  You're on vectors, so don't turn until told to do so.
If you go lost comm, then AVE-F would tell you that you're on Vectors to WINCO, so get yourself there as best you can, probably by turning direct if you're RNAV equipped, or flying the radial if not.
EDIT: Note, though, that in the normal (with comm) case,the DP instruction is NOT to fly heading 273 to intercept the radial; it is to fly that heading.  That's your only CLEARANCE.  ATC will turn you to intercept on whatever heading they want you on.  Only in the case of lost comm would you turn to WINCO upon reaching the 322 radial.  In all other cases, follow ATC instructions.

Doesn't the text "From over DHP VORTAC on DHP R-322 to WINCO INT" mean you should expect vectors DHP, DHP 322 WINCO? ("expect" from AVEF, not what you're likely to get...)

No, that's not what it actually means, although that's not an unreasonable first guess.  As noted in the OP, DHP is in the wrong direction, and if you're comm out, ATC will want you flying TO the WINCO waypoint, not away from it to DHP then spinning on top of the VOR and THEN heading toward the waypoint. While WINCO may be defined off of several VORs, they routing they want a non-RNAV aircraft to take to get there (and to be ready for) is via the DHP 322 radial.  No good purpose is served by flying to DHP, and that isn't what those instructions are telling you to expect.

Agreed that flying to DHP isn't a great routing - but why doesn't it say "Intercept DHP R-322 to WINCO INT"? You can do that in a non-RNAV aircraft.

See my edit above. The departure COULD say that (fly heading __ to intercept __), but that would be a different departure.  This one is a vector, pure and simple.  ATC will tell you when to turn.  The DP tells you what routing you can EXPECT to get, but that's only an "expect," not a clearance until ATC assigns it.

Too much back and forth... let's continue this in chat.

I agree with your interpretation, and it is the way I would fly it. I do believe that the FAA TERPS squad have been loosing the ability to write a procedure in plain understandable English. Specifically -- From **over** DHP VORTAC on DHP R-322 to WINCO INT is confusing.

@dawg Note that it says to expect vectors to appropriate transition and then goes on to define the transition as being from DHP to WINCO. It never clears you to fly to DHP...

@Lnafziger: Key parts of the question are what do I do in lost comm (so you cannot receive vectors) and the text From over DHP VORTAC. Almost every clearance I get states something like "Climb 3000, expect Flight Level 320 10 minutes after departure..." That is for lost comm; if communication cannot be established within 10 minutes of departure , you climb to FL 320 as instructed. You do not climb if have communications. Similarly here - My question is, if I do not hear otherwise (lost comm) do I fully execute the part From over DHP VORTAC and if so, what does that mean?

@dawg I agree completely with Ralph's answer, and was simply pointing out that DHP was never included anywhere in the instructions, other than to define the transition. You are receiving radar vectors to WINCO, so if you go lost com you should follow lost com procedure appropriately.

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Where to find information about number of seats knowing the aircraft Registration ID?
Let's say I have an aircraft registration id (not sure about exact name) like LN-DYO. Where can I find an information about configuration of the aircraft - i.e. number of first class seats, business class and economy class seats? I would like to have some automated solution (API? parsing of web-pages?) to get this data for a number of aircraft.

I seriously doubt there's any system that would have such information for a non-trivial number of aircraft.
Not only is the information pretty irrelevant except for the purpose of internal planning by the owner/operator of the aircraft (who obviously have it for their own aircraft in their internal systems), it's also liable to change suddenly.
For example Martinair flies (or flew, they may have retired them) several MD11 series aircraft that had palletised passenger cabins. These aircraft could, within a few hours, be converted between passenger and cargo configuration as needed (and I think could even be operated with partial passenger cabins). Such a source as you're looking for would never be able to reflect that.
Then there's the 747 Combi variants that used to be operated by KLM which had similar arrangements (but were permanently set up with only partial passenger cabins, an arrangement that could have been changed).
Aircraft may also go in for refurbishment and receive entirely new cabins with different layout. And that can happen without the aircraft being sold, just because the owner changes their business plan (e.g. they might reduce the number of business class seats on some aircraft because of reduced demand for them, sometimes even temporarilly, for example during the summer holiday season when business travel is slow).

So the source would need to get constant updates from people who have far better things to do than provide such updates, as they have no need whatsoever for the service that that source might provide.

Thanks for so detailed comment. Understand that what you've described could be a case. But when tickets being sold, we know for sure how many seats are available, right? Doesn't it mean that some systems (like QPX) can have some historical information (which will be up to date more or less)?

@LA_ do you know? Really? You might get a graphic showing a cabin layout so you can select your seat, but do you know whether that's exactly what will be in the aircraft when it's time to board? Or whether all those seats are for sale?

As a customer, I don't have such information. But as an airline, if you start the sale, you should know which seats are for sale (configuration is not so important as number of seats). Or, does it work differently - for ex., airline starts to sale 100 economy class seats, if all are bought, then one aircraft is used; if only 50 are bought, then another?

@LA_ yes, and the airline has no incentive to give that information to a third party. What's in it for them? Nothing at all.

Saying 'yes' do you confirm my first statement (=aircraft is known when sale starts) or second (=aircraft is chosen when sale finished)? ;)

@LA_ I seriously doubt the specific aircraft to fly the leg is known when ticket sales start. After all, sales often start half a year to a year in advance of the flight taking place, the aircraft may not even have been delivered at the time... What will be known with some degree of certainty is the aircraft type and with that the most likely cabin configuration (many airlines will have very similar cabin configuration across their fleet for a given aircaft type, though there may be differences).

The usual way would be to find out which airline operates that aircraft. Usually Google will give the answer. Otherwise planespotters.net will help. In this case it is Norwegian.
Then seatguru will show you what the interior configuration is.
I don't know whether these website have public API's that could help you and I think that is a bit off topic for Aviation.SE.

Thanks. Flightradar can also help to identify which airline operates the aircraft, but the main question is about number of seats...

@LA_ You can see the number of seats on seatguru can't you? In this case it says 186 Economy Class seats.

Unfortunately, seatguru doesn't have information about many airlines I am looking for.

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Why wouldn't a helicopter ejection seat eject sideways? Or forwards?
This question got me thinking. Ejecting from a helicopter is necessarily more complicated than ejecting from a fighter jet or other fixed-wing aircraft. The answer to this question states that ejection-capable helicopters blow the blades first, then the canopy, then eject the passengers.
This seems to me like a lot of explosions above your head, which seems only slightly preferable. Why not eject the passengers either sideways or forwards?

This would not work so well at low altitudes, especially at the strange attitudes a helicopter requiring ejection would probably be in.

There are a lot of trade offs here, like space, weight, cost ,reliability, and use constraints, injuries to the person. Honestly, it's quite controversial whether ejection would help much in a helicopter at all, or under what conditions ejection has the advantage over not to eject. In reality most of the unconventional eject directions (down wards, side ways) usually have very tight use conditions and high failure rates.

If your question is specifically about Ka50, then a reasonable guess is, this use case is targeting low altitude usage (it's an attack helicopter) so you need to maximize altitude to deploy parachute reliably.

I wouldn't like to be in this helicopter in a nose-down position at low altitude when ejecting forward

Good way to paralyze somebody, snap their neck moving sideways at quite an incredible speed. Spinal injuries are relatively common in normal ejections going straight up where the force vector is basically in-line with the spine. It would be like being kicked in the head by a professional soccer player.

Well to me it seems that in your question you consider the helicopter flying straight and level and clear of any terrain. Well that's not true so let's take each case separately:
Eject forward
That seems like the most dangerous option to me. What if you are into CFIT? The ejection system will actually "spit" you into terrain with your helicopter's speed plus the speed of the acceleration. Ouch. Even if you survive this, the point is to escape the helicopter. And guess what its trajectory is: forward.
Also consider that the free stream works against you so you will need more acceleration to get away of the incoming helicopter.
Finally, right in front of you there is equipment like dashboards, machine guns, sensors, etc. that need to get out of your way before you go.
Eject sideways
That sounds a less dangerous option. But what if the helicopter is banking to one of the sides? If the crew is seated side by side do they have time or even the option, "I go first you go after"?
Also bear in mind that attack helicopters' nature is to fly low and maneuver a lot. So there are high chances to be low and bank at the same time when in need to eject.
So the above 2 leave you with one option: eject upwards. But then you have one (or maybe 2) big propellers rotating above your head. But that's "easy": you get rid of them the same way you get rid of the canopy and then eject. Once the blades are released, the centrifugal force will do what it knows best and the blades will be out of your way in no time. Well, hopefully.
Considering the "too many explosives above ones head", it's not a rare practice to use explosives to get rid of things that are in the pilot's way like for example the canopy. That's been around for a while. But changing the trajectory of escape that will be a new concept and it will need lots of testing.

This is a very well thought out answer that explains it in laymens terms. I'd +2 if I could

@Sidney thanks, glad I've helped.

I'd also say that the human body will survive a forward acceleration quite well, while upwards can result in serious injuries. But sidewards sounds really sad.

Also, I can think of a few scenarios where a forward ejection, even if it successfully ejected you forwards and safely deployed the canopy, the helicopter which might have been traveling forwards, could quickly catch up with the occupants, and if the rotors don't get the canopy, the body of the aircraft could also hit anyone that was ejected into the flight path of the disabled helicopter.

Wait, what happened to backwards?

@JollyJoker good question! But you should really ask the OP! :) I quote: "Why not eject the passengers either sideways or forward"

@JollyJoker Assuming that's not a tongue-in-cheek comment, the engine happened (to be in the way).

@AEhere Maybe in most existing helicopters, but I guess you can work around that if you really need to.

Ejecting from side-by-side seating while banked? That's simple! You just eject both seats "up hill"! Oh, but then you have to have two separate but interlinked sets of ejection rockets, one to eject left, the other right, then you need a functional sensor in a time of crisis to know which way is up, then you need a way to only fire the correct set of rockets and not have them set off the other rockets, then you need to make sure that the rockets of the first seat don't roast the guy in the second seat, then.... Yeah, I guess up past the rotors is easier.

@FreeMan I think that sideways ejection has many more problems than just "ejecting while banking" that I originally wrote. I didn't want to overanalyze it though. I don't want to know what would happen to one's neck and spine if they suddenly get "Hulk punched" sideways... PS: thanks for the grammar editing. At least I now learned that et al. goes to persons and etc. to objects. :D

That was intended to be a somewhat satirical analysis of what might be involved, and left out quite a number of important bits, I'm sure. Sorry, mom was an English major and my dad has his PhD and was listed before and included in several et als. These things were pounded into me young and sometimes come out at the most inappropriate times...

Because of a high chance of being launched into terrain, not because it would be worse for the body.
The human body can actually withstand more g's in forward and sideways acceleration than in upwards acceleration. When accelerated upwards, the blood cannot reach the brain and eyes and very soon a glucose deficit will cause loss of vision and/or of conscience. Colonel John Stapp pioneered building up this knowledge between 1945 and 1958, by exposing first a dummy and then himself to accelerations up to 46.2 g. From this fascinating article:

Stapp was subjected to tortuous conditions, but more importantly, he survived. His team showed that humans could withstand forces in excess of 30G deceleration and just as importantly showed that seats, harnesses, and cockpits should be designed to withstand these forces as well.

And

Stapp had suffered a complete red out and was just barely conscious. The jolt burst nearly every capillary in his eyeballs, he was blinded, but his retinas did not detach. He slowly regained his bearings and within a day his vision was back to normal.

Results of the research of this brave man:

Forward acceleration up to 20G is perfectly survivable.
Backward acceleration is much more taxing to the body.
Sideways acceleration has little influence on consciousness, but does have significant impact on supporting muscles for the head. So the head must be fixed in sideways position before ejection.
Upward acceleration is more taxing than in x- or y-direction, with problems occurring at 4-5 g depending on onset and duration. A typical Martin Baker seat creates accelerations of 12-14g but for a very short time.
Downward acceleration is tolerated the least well by the body.

Image source
So for the body, x- and y-accelerations pose fewer problems than z-accelerations, provided that the head is supported for sideways acceleration - the Formula 1 style may be too restrictive for helicopter pilots though.
The first F-104 Starfighters had downward facing ejection to avoid the T-tail, however they fly quite a bit higher than a typical helicopter. The main practical problems are therefore altitude and attitude. Upwards is a better direction!

While it's true that being unconscious generally tends to disable one's conscience, I'm thinking that you meant to say "consciousness" instead?

If the picture of Lewis' helmet is to show the HANS device, then your example is wrong. The HANS device is designed to restrict forward motion of the head in a frontal accident (equivalent to ejecting backwards), not to provide side-to-side protection. The cockpit of an F1 car has a large padded surround that gives the driver about 1-2" of lateral movement before hitting foam that is designed to deform and slow lateral movement in an accident.

The foam is so close fitting that it's removable to allow entry and generally removed for exit from the car, though drivers can get out without removing it when necessary (like after a crash).

In both cases, you must be sure to "outrun" the helicopter blade. Your seat must go fast enough to avoid you getting a new haircut. This might be problematic because of violence of the acceleration, especially if you eject sideways.
In addition, helicopters tend to fly low so you might hit terrain or simply not have enough altitude to land safely.
I'd rather have explosions above my head and eject safely than ending like a pancake or minced meat.

Best answer:  The problem has been considered and, for typical low altitude operations that helicopters do, a sideways or forward firing  ejection seat would not offer a sufficient vector and time to ensure proper recovery parachute deployment.  This was largely negate any kind of safety capability a seat with offer. Certainly forward or sideways fire in ejection seats could offer a suitable escape system at higher altitudes but must combat and attack helos operate at treetop levels.

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Why do aircraft with turboprop engine have black painted anti-icing system?
Everyday as I watch aircraft with turboprop engines, a question pops up: Why do aircraft with turboprop engines have black painted anti-icing system?
For instance:

These are rubber boot deicing systems. When ice forms on the leading edge of a wing, pressurized air is used to inflate the boot so the ice will pop off. Normally, this inflation is not permanent but the air is pulsed. Activation is done by the pilot, so this system is normally switched off. Operation needs some care because if used too late (with too much ice) the boot may become impossible to be inflated.
Historically, it was believed that activation with too little ice would also render the boot ineffective, with ice building up around the inflated boot (ice bridging). This seems to have been a myth.

Deicer boots in operation (source: Wikipedia)
Other deicing systems use heat or constantly seeping deicing fluid. The first method is normally used on jets with bleed air or electricity as the heat source. The second system was for example used on the Beech Starship which had a titanium leading edge with millions of tiny, laser-cut holes for the application of deicing fluid.
Alternatively, surfaces are designed large enough to still be effective under icing conditions.
Fast jets do not need a deicing system - their stagnation point temperature is sufficient to remove ice. However, ice can still be a problem: When the supersonic B-1A was converted into the more stealthy, but subsonic B-1B, ice buildup inside the intake (which now had obstructions added so the engine compressor would be hidden from radar) would result in large chunks of ice building up, then breaking loose and damaging the compressor blades.

The theory of ice bridging is now disputed by the FAA, at least for contemporary systems.

Airliners can take some credit for compressibility heating and generally aren't required to have wing anti-ice on above a certain speed, like 230 kt, when in technical icing conditions unless the ice detection system senses an actual accumulation on the probe.  On the other hand, cowl anti ice has to be on at all speeds when in visible moisture when close to or below freezing.  In any case, military fighter aircraft have to avoid icing, which is kind of odd for those that are considered "all-weather" interceptors..

I don’t believe the Beech Starship used a hot prop as the pusher design allowed the exhaust from the PT6 engines for anti-icing on the blades.  Same as the Piaggio P.180 Avanti.

@CarloFelicione, where do I say that the Starship props had thermal deicing? I talk about the wing and its use of deicing fluid.

@PeterKämpf why not let the air flow out of the boot after application, so you could inflate it again at a later time during flight?

@ROIMaison Air is cycled into and out of the boot so it vibrates. Its is not pumped up like a ballon and left that way - this would harm the aerodynamics.

I'm no pilot myself, so my comment might be of little value, but... saying that you shouldn't activate the deicing boots too early to prevent bridging sounds like dangerous advice.
Comair Flight 3272 crashed because the pilots were training to not use deicing boots prematurely, while that advice is outdated and not supported by any factual evidence. The NTSB report of that crash recommends activating the boots at the first sign of icing.
The FAA, NTSB and NASA have been saying ice bridging is a myth that should be eradicated asap for a while now.

@Opifex: I have been educated when ice bridging was still part of the syllabus. I guess I should rewrite that part of the answer.

I can serve as a second data point. 50% of my time is flying commuter class propeller driven aircraft. I have spent a lot if time in ice. Not once have I seen ice bridge and I've gone out of my way to make it happen.  All of my training told me that ice bridging was real.  It's not.

@acpilot Thank you, that is very interesting. Now I wonder how the ice bridging myth ever came into existence. Is the current wording of the text fine with you?

Your answers are always perfect.

They're not painted black, but a rubber (hence black) device called a de-icing boot.
Upon entering icing conditions, the system once activated will repeatedly inflate and deflate the rubber boots. This will destroy any icing build-up.
Larger jets use a system where the leading edge is heated by bleed air. This requires a lot more bleed air, but has the advantage of not deforming a wing while traveling near the speed of sound.

Why don't turboprops use bleed air for deicing?  Is it because they don't have the bleed air available that a turbofan has, or is it because it's bad to deform the wing when transonic?

@Wayne I didn't include this in my answer because I'm not an expert, but my guess would be a bit of both.

As the other answers have already pointed out these black areas are not painted, they are rubber surfaces that are inflatable to break off any ice that forms on them.
To produce rubber you need a filler. The main "rubber" producer, tire factories, use carbon black (soot) because it is cheap and tested. It also dyes the rubber black. However there are other options available and rubber can be dyed any way you want.
For the aircraft de-icing boots it is sensible to choose a black rubber material. Think of the cabins, they are mostly painted white to reduce the amount of solar radiation the cabin picks up, reducing the need for air conditioning. For the leading edges of the wings, when they are in danger of icing up, you want them as hot as possible (well, not too hot...), so just make them black.

Congrats! This is the one answer that addresses why the rubber is black!

Also, carbon black protects against UV degradation. UV intensity increases by approximately 4% per 1000 feet of altitude (ref: An NIH document).

It could also be desirable to see white ice against a black background

I can't imagine the colour would have any noticeable impact on temperature. Forced convection from freezing air and conduction from ice accretion will be much more significant, and at night black will actually be colder than white.

That said, it's useful to point out that not all deicing boots are made from black rubber.

The thermal theory has one slight problem; the sign is wrong. Black materials warm up in the sun, but they also cool down faster in the dark. And icing is more a problem in the latter circumstances (consider the long winter nights near the poles).

@Sanchises Try to quantify those effects. For normal objects around us exposed to the wind the temperature is crucial. Now, the air flow is much faster there, but you still cannot dismiss the radiation so easily.  At night it would be cooled indeed, as the infrared emmisivite does not differ from the visible one too much.

This is the correct answer. Raw rubber is NOT black in color. Natural rubber is light in color and often even transparent, but it is also not a very good material on its own. The boots are black for the same reason vehicle tires are black. Carbon black, a material produced by the incomplete combustion of heavy petroleum products such as FCC tar, coal tar, or ethylene cracking tar, is added to the rubber to improve the rubber's characteristics. The addition of carbon black makes the rubber more heat- and abrasion-resistant, tougher, more resilient and long lasting.

However, "to produce rubber you need a filler" is incorrect. To produce the material that is used for tires and anti-ice boots, among others, the filler is added. Rubber bands, for example, are not made with carbon black filler.

authors: Vladimir F Героям слава


text:
Why is the cockpit color of eastern aircrafts different than western's?
Commonly, the cockpit of eastern aircraft have a MediumSpringGreen or PaleTurquoise color while the cockpit of western aircraft have a Black or Gray or SaddleBrown color. Is it kinda standard? e.g.
Tupolev Tu-142M3

Ilyushin IL-86

Boeing 747-84AF

Beechcraft B200GT Super King

Note that most common colour in western cockpits is probably gray, often with hint of the same turquoise as Russian manufacturers use, though never that saturated.

I don't think this is a duplicate. The other question was "Why are Soviet aircraft cockpits green", while this one is "why are Western and Soviet cockpits different colors?" If the Soviets found out that blue-green was the best color for cockpits, why didn't Western aircraft manufacturers adopt that color scheme as well?

@nick012000 This is not the first time for me. e.g. https://aviation.stackexchange.com/questions/83122/whats-this-outlet-of-iae-v2500-for

@nick012000 (and Roh) if you think this is not a duplicate vote to reopen or, if you can't vote to reopen, please start a discussion on meta

@Federico I can't vote to reopen, which is why I left a comment and flagged the question for moderator intervention.

@nick012000 opening a discussion on meta is better than asking for moderator intervention


text:
Could a golf ball damage an airliner?
Question
Would a golf ball ingested into an engine, or impacting a windshield cause meaningful damage to a commercial airplane?
The scenario below outlines that this is possible, but the principle question is: would it actually matter, as in, would it cause the same level of damage as, say, a strike from a single bird?
Plausible Scenario
At McCarran airport in Las Vegas (KLAS), runway 1R is situated just across the street from a driving range. Several years ago, I was hitting balls on this range when a 747 landed on 1R. It seemed impossibly low; many people on the range stopped hitting to point and take pictures. For context, here's a video (not mine) taken from nearly the exact same spot, with an approach to the same runway.
At the time, I remember thinking "That plane is very low... what if it got hit?" Appearances are often deceiving, so my initial assumption was that it must be higher than I thought, so a did a bit of basic trig to find out:
The touchdown markers on 1R are about 4,250 feet (red line in picture below) from the top-level hitting stations. With a 3 deg. glide slope, the plane would have been roughly 225 feet above the ground when passing over the driving range (slightly lower down range when balls that have been hit are at their highest point).

(Image: Google Earth; own drawing)
With a 21-degree 7-wood which I hit about 200 yards, the ball would reach an apex of around 230 feet.
So, wind, timing, and the quality of golf shot actually struck notwithstanding, it seems at least possible that a ball hit from off that range could hit an airplane. In other words, the "bounding box" of the plane at least theoretically intersects a line representing the maximum height of a shot from the driving range. Thus, it seems unsafe, even if the chance is 1:1,000,000 (or greater).
I have to assume that since KLAS is one of the busiest airports in the U.S., that this is not actually an issue, otherwise changes would already have been made.
However, if an impact or ingestion were to occur, are there circumstances where it would be a "significant" event?
Notes

No one, esp. myself, was trying to hit the plane.
Despite #1, there are at least 50 hitting stations, which means lots of shots in the air as the plane is passing over the range.
This is Vegas, and alcohol is served at that range. People do try, sometimes, to hit the guy in the little range car. I doubt that would ever carry over to a plane, but it can't be logically ruled out.
My concern is that even without anyone trying, a ball could still impact the plane. But would it matter?

There is Golf Course between 2 runways of  DMK airport

Very interesting question! Couple of thoughts: by the time you see an aircraft in front of you, your golf ball may have a hard time chasing down & catching a 150~ mph jet. What sort of velocity can you get on a drive like you describe? Also, at least 1, maybe both, of the north runways in LAS have steeper-than-standard approach angles. I’ll have to check which; this could be the reason. A golf ball thru the core of a motor would certainly be bad for it. Very interesting question - well done indeed!

Scratch that theory... the RNAV approach to 1R is a 3 degree angle. It’s the ILS 1L that is 3.4 degrees. So they didn’t change the approach based on this situation. For any single flight, it’s a pretty unlikely “golden bb”, but with enough flights (and enough golf balls)...

Just to be clear, is this a question of a deliberate attempt to do harm; are you concerned about a possible accident; or are both possibilities to be addressed?

Most definitely the latter. Not that a full accident would result from impact, I think, but to have such a large plane go directly overhead while you’re hitting is stunning. For me at least an initial thought was “this does not seem safe!”

Roughly 2 years before this question was asked, my son and I stood in front of the building in that picture. We were waiting for someone to come pick us up after he twisted his ankle at a gymnastics meet inside that building. I took a number of pictures of planes taking off. I don't think anyone would have had a chance to hit a plane with a golf ball on take-off, so that point (though not asked about) is moot.

@FreeMan For take off, definitely not. A departing plane would already be significantly higher than the 225 ft. I calculated for landing. For landing, it's definitely in the realm of possibility, but both exceedingly unlikely and, as answered below, possibly of no consequence anyway.

Not that it says much, but golfing is prohibited at the famous Myrtle Avenue spotting location next to London Heathrow by a dedicated sign posted there. Could be to protect cars on nearby A30, not aircraft, though...

Turbofans on commercial airliners are tested against hail, up to 'golf ball size', and ice is harder than a golf ball.
Think back to Taca 110, that lost both engines while descending through a hailstorm reported to be up to golf ball size. What killed the engines wasn't the impact of the hail, but the amount of water ingested into the engines. It seems that the engines had been tested for water and hail ingestion at cruising speed... not at near idle, which was the power setting during a descent. Once identified, that problem was rectified quickly with mods to the engines.
Nor does the golf ball have the sheer mass of a goose, such as the flock of geese that took out both engines of USAir 1549.
Most likely, a golf ball striking a running turbofan would be sliced up by the front fan, and centrifugal force would tend to fling the fragments outward where they would exit via the bypass, and not through the turbine engine.
So I'd have to say, very unlikely, only to allow for the chance in a billion that the sliced up fragments of a golf ball might actually enter the compressor stage and cause a problem in one engine.
The greatest problem from a golf ball being ingested by a turbine, is figuring out what rule of golf applies... how do you mark your card? (WTF probably doesn't meet approved guidelines)

I think it's fair to say then that one golf ball sucked into an engine wouldn't be significant damage. Thanks! As for golf, I'm pretty sure you'd proceed under Rule 18-1, so the airplane-shot would be cancelled and you'd play again from the same spot.

I dispute the part that ice is denser than golf ball. Ice I see always float but whenever my golf ball goes to the water it always sink.

good point... perhaps it's fair to say that ice is harder than a golf ball, and thus more likely to produce damage if struck by a moving fan blade.

Not Rule 11.1? You don't think the ball needs to be played from the gate after the airliner has landed? ;-)

Smarter Every Day just published a video on how hard you can hit a golf ball. It turns out golf balls are incredibly strong, so I'm not sure it would be 'sliced up by the fan'. I suppose realistically the only solution is to buy the Smarter Every Day guy a turbofan to test it.

@Sanchises: Golf balls may be incredibly strong, but turbofan blades are also incredibly strong (for reasons like this).

Is there a risk?  Possible but I'd say negligible.
A typical champion golfer can drive a golf ball with a departure velocity of about 150 mph or so from the tee.  That's fast but atmospheric drag quickly slows the ball down to around 50 mph or so by the time of impact back on the turf.  Golfball drives from even the best athletes only gain about 90 feet of altitude during a typical drive, making it highly unlikely that that a drive could launch a ball to even the ILS decision altitude of 200 feet AGL.  With a typical jetliner flying an approach at 140 knots (161 mph), it's highly unlikely that a golfball could catch up to the aircraft in flight as well.
But even if you cold drive a golf ball with a herculean effort, as any anti aircraft artillery gunner will tell you, it's extremely difficult to hit a moving aircraft using unguided fusillades.  Golfers have enough trouble aiming for a putting green, taking into account position, obstacles, winds, etc. to have to add in the additional difficulty of hitting an airborne and fast moving object as well.
Now should a golf ball hit an airplane, yes there is a change to damage it similar to an errant drive hitting a car.  Superficial dents or scuffs would be anticipated.  It might damage an aircraft window, though I highly doubt it would shatter, particularly windows on pressurized aircraft.  Golf balls ingested into engine intakes and or propeller arcs would be pretty hazardous for the aircraft as well.
So who knows, maybe someone here can dig up a wild story from the past where a golfer nailed a low flying 707 with a drive and took out an engine, but I highly doubt it's possible and really not even a risk at that distance from the airport.
Now a pilot with an engine failure shortly after takeoff and makes a forced landing onto a golf course, only to have an ill tempered golfer fire a drive at his airplane out of ire, that's another possibility.

The question appears to ask "Can a golf ball do damage?", not "Could a golfer hit an airplane (from this spot)?".

I'm not sure why a golf ball would have to catch up with the airplane, in the same way that birds don't have to catch up to be stuck by an airliner. Besides, the golf course is about 600m from the runway threshold, so chances are that the airliner is already below DH (and why should DH matter at all?)

But the course is about 1 km from the touchdown markers of the runway and the glide slope antenna, which would correspond with approx a 200 ft height for the jet on final approach, clearly out of range for even the best golfers.

It would be incredibly tough to hit a plane with any given shot. I think the premise of the question is not an intentional strike, but just the fact that there are hundreds of planes and hundreds of balls in the air in close proximity and potentially there is an accident there.

@Thomas Yes, that's exactly what I'm saying.

@CarloFelicione I agree with your conclusions, but asked the question in hopes of finding actual evidence one way or the other. e.g., has some test lab thrown one or more golf balls (or small rocks) into a running engine, and what was the result?

I doubt it, considering a golf ball is really not considered a readily encountered hazard while flying or for ground operations.

This is an answer to a slightly different question: Could a golf ball damage an aircraft?
The answer is yes, at least indirectly, as it has happened  in 1987 in Benin.
Basically, this golfer hit a bird with the golf ball. The bird fell into a fighter on takeoff with the canopy open (or hit the windshield, unclear). The pilot lost control of the aircraft and subsequently collided and destroyed several other planes on the apron.
Refs:

PPrune
Google
Book: The Golf Hall of Shame

I hope this isn't some kind of urban legend...

What are the chances :D

I have to object here. It is grossly misleading to say the golf ball damaged an aircraft when in fact it destroyed or damaged the entire air force. LOL, thanks for this.

Spectacular.  Thank you  for  sharing!  I'm sure it must  be true.

Fore!


text:
Has any jurisdiction mandated passenger training?
A chunk of pre-departure time for each flight is dedicated to a safety briefing for passengers that few passengers seem to pay attention to. In the aftermath of accidents, it has been revealed at least a few times that passengers did not listen to or understand the briefing, or in the panic of the moment, forgot all about it.
A couple examples:

Southwest 1380: Air masks not properly worn
BA 2276: Taking bags off during emergency evacuation

With this in mind, has any civil aviation jurisdiction ever considered or implemented mandatory passenger training for commercial flights? (In the form of a short annual/bi-annual course requiring a passing grade in order to be allowed to fly. Sort of like CPR training, but for airline emergency procedures.)
Curriculum could include:

Knowledge of oxygen mask usage
Ability to exit plane properly during emergency (closest exit, no belongings)
Emergency door operation
Wayfinding in smoke-filled cabin

I'm not advocating for this, or suggesting it would be effective, but curious if it was ever considered, especially in the 50s or 60s when air travel was still relatively new (and somewhat more dangerous).
In the context of this question, I'm asking if a regulatory agency has attempted the above, not an airline or airport operator. Regulatory authorities are the one who require the current safety briefing approach.

What is the difference between the "passenger training" that you described, and the passenger briefings that already happen?

The crew is required by law to provide the passenger briefings today. Is your question whether anyone requires the passengers to actually pay attention? As a practical matter, I doubt that is possible...

Edited to be specific, let me know if not clear enough.

You can't force paying passengers to listen to or pay attention to anything the crew says. That is a conscious choice, and falls under the category of #YouCantFixStupid.

@JuanJimenez, yes for sure. And to reiterate, I'm not saying would be a) possible, b) a good idea or c) has ever happened. But I can imagine a certain type of authority that would think it's possible, and so am curious if that ever happened.

The offshore oil industry does require helicopter survival training for its employees. You actually get dunked in a cabin simulator completely underwater with rollovers. These are commercial flights, though you're probably thinking of air carrier flights.

some places offer course for business passengers who regularly fly in smaller planes, i dont know of anywhere this is regulated.

@Dan1701 I would love to see airlines require passengers to view and complete a short online course on safety and passenger responsibilities.

@JuanJimenez I'm agnostic on whether it should be done or would be useful, but I was curious if it had been done anywhere, so that the results could be examined. Mostly I find the pre-flight safety demo useless and was pondering if anything more effective might ever have been tried.

In Canada and the US many government workers flying small planes/ helicopters are mandated to take emergency underwater egress training, not sure if this counts as regulation, but it is a government requrement.


text:
How can pilots minimize parasite drag?
What can pilots do to minimize parasite drag?
As far as I know the effect of parasite drag really depends on the manufacturer of the airplane, but can pilots do anything about it?

About all I know a pilot can do is to fly it trimmed and wash it once in a while...

fly higher, or at least high enough

One of the guys flying my Cherokee wanted to go faster and looked into all of the speed mods available. http://www.loprestiaviation.com/aerodynamic-mods-6/pa-28-s-cherokee.html He decided that the cheapest way  to go faster would be to buy a faster airplane.

Parasite drag is for the most part out of a pilot's hands, as it's a combination of:

Form drag: drag from an airplane's general shape
Interference drag: drag from airflow mixing around parts of the aircraft structure
Skin friction drag

You can reduce skin friction drag by keeping the airplane clean, dirt and smashed bugs cause friction, removing them reduces friction. You can also make sure all the little doors are flush. Other than that you can't do much without making changes to the airplane itself, for instance:

Flush fuel caps
Wheel spats: these aren't decorative, they reduce the wheels' drag by providing an aerodynamic cover
Seal kits: these reduce interference drag by smoothing airflow
Cowling replacements
Fairing replacement

Whether these are worth the cost depends on the airplane, Cessna 152/172s are very draggy to begin with because of their rivets and wing struts, you could dump thousands into additions for very little benefit. Other airplanes get measurable improvements in speed from a few seals here and there.

Pilots can help keep parasitic drag to a minimum by:

closing all doors, hatches and windows
retracting the landing gear ;-)
keeping seatbelts from hanging outside of the aircraft during flight
not adding GoPro cameras to the outside of the aircraft

Some competitors at the National Championship Air races in Reno, Nevada, depending on class, will tape-over wing and fuselage seams and gaps. This is commonly seen in the Sport Class where general aviation, kit based, planes compete.


text:
What written tests are required to become a ground instructor?
What are the written tests required to become a ground instructor? Do I have to take the FOI, BGI and IGI? Or just the FOI and IGI tests?
I got confused if I should take the whole three tests - FOI, BGI, IGI - or if just the two IGI and FOI tests are enough?

The AGI covers all of the BGI info, so you want to take it instead. IGI covers instrument only. FOI is required for any ground or flying instructor unless you are an active teacher at a school or college.

The FAA offers some nice guidance here

You may also want to check out my answer (a very close to dupe) here.

Am I reading this table wrong? I t looks like you can get an AGI just by taking the BGI and IGI, without either the AGI or FOI?


text:
Does an active pilot based outside the US require a flight review to maintain FAA currency?
If a pilot is a holder of both Canadian and FAA commercial pilot certificates and is flying regularly in Canada, does this pilot still require a Flight Review to maintain currency of their FAA certificate?

Are you in a WINGS program?

Welcome to aviation.SE!

Transport Canada tried to impose its own version of biennial flight reviews in the late 80s, but after a storm of opposition from the GA community, it was watered down to a requirement to take a short at-home self study test or attend a safety seminar every two years.


text:
What is the real difference between aerospace and aeronautical?
I see people using these two words interchangeably. But I feel there is a huge difference between the both.

Have you tried looking up the words "aerospace" and "aeronautical" in a dictionary? If so, what do you find unclear about the dictionary definitions?

Aeronautics is a subset of aerospace.

Aerospace is the human effort in science, engineering, and business to fly in the atmosphere of Earth (aeronautics) and surrounding space (astronautics).
  source: https://en.wikipedia.org/wiki/Aerospace

They are, somewhat incorrectly, used interchangeably - to colloquially refer to the broad subject of "flight".

Additionally, some institutions have stuck with the "aeronautical" moniker for a very long time, since before spaceflight was possible, which has conditioned the speech of their alumni. My own diploma says aeronautical engineering, even though the curriculum had spacecraft and orbital dynamics as core subjects.

There is indeed a fundamental difference between spaceflights and aeronautics. But historically, the space industry largely grew out of aviation, NACA became NASA, etc. There is a lot of shared knowledge and experience; many companies are active in both fields (Lockheed Martin, Boeing, etc.) An overarching term to cover both fields makes sense.
However, this is not a universal truth. In the USSR, for example, the postwar history went such that the space industry grew out of (and initially was managed by) the artillery. And although some aeronautics companies were later forcibly converted to space, there was no shared industry to speak of, and the term 'aerospace' was not in common use.


text:
What is the correct go-around procedure in a PA-44?
I wanted some advice on a procedural-type question. In the PA-44 (Piper Seminole) go-around procedure, it is listed as follows:

MIXTURES ............................................FULL RICH
PROPELLERS ............................................ FULL INCREASE
THROTTLES.............................................FULL OPEN
Control Wheel...........................BACK PRESSURE TO OBTAIN POSITIVE CLIMB ATTITUDE
FLAPS....................................................RETRACT SLOWLY
GEAR.........................................................................UP
COWL FLAPS........................................................... AS
  REQUIRED

(You can find this on any online version of the PA-44 PIM - here's an example on page 4-17.)
Now, the way I have always been taught is to go full throttle, carb heat off (not listed in PIM), flaps 40°->25° immediately, then 25°->10° at positive rate, and 10°->0° upon being above Vy, then gear up, and cowl flaps open.
I began researching the Airplane Flying Handbook and it states in the Transition to Multi-Engines section (page 12-18) that:

With sufficient airspeed, the flaps should be retracted from full to
  an intermediate position and the landing gear retracted when there is
  a positive rate of climb and no chance of runway contact. The
  remaining flaps should then be retracted. [Figure 12-10]

My question is this: would a better go-around procedure be full throttle, carb heat off, bring the flaps to 25°, then gear up, then continue as previously specified? This would reduce the drag the gear is giving a lot sooner, briefly take advantage of the increased lift coefficient 25° degrees of flaps gives (that is the specified flap setting for the short field take-off), and also follow the AFH procedure.

I would suggest discussing "back pressure to obtain positive climb attitude" with full flaps with a qualified instructor.  Generally you go full throttle and check airspeed before retracting full flaps to partial flaps.  The only case where elevator is applied before power would be rounding into ground effect (nose down near the ground).  "Sufficient airspeed" is vital (accelerating in a slightly nose down or level attitude - planes will climb with full power) is a key concept in avoiding power on stalls.

At full power drag from gear is the least of the worries.  Gain speed and retract flaps.  Begin climb, gear up.  If I were training in this type, I would see how steep an approach (dive) angle I would have to be in before adding power alone does not arrest descent.  It may be a lot steeper than most approaches to land clean or dirty.

This just in for the PA-44:  Vfe 111 KIA Vle (landing gear extended) 140 KIA Stall speed clean or dirty under 60 KIA.  Looks like you have some room to work with.

Any procedure listed in the AFM for your airplane takes precedence, but a general go-around technique I use (and teach my own students) is as follows
1) Add power - on complex airplanes, verify mixture rich (or for best power at high altitude airports) and propeller controls are set for maximum RPM prior to pushing the throttles to full power.
2) Apply aft elevator pressure to arrest rate of descent and bring nose level with horizon.
3) With level flight attitude, set flaps from full to approach setting.
4) continue applying aft elevator pressure and establish climb attitude
5) Once climb attitude established and continuous positive rate of climb confirmed, retract the gear.
6) At sufficient airspeed and altitude to permit safely doing so, retract the flaps.
7) Set throttles and propeller controls for maximum continuous power and pitch for selected climb airspeed.  Trim aircraft to neutralize control pressures.


text:
Does anyone know what this approach chart symbol is?
Does anyone know what the little “shell” like symbol on the taxi diagram is, under the 2239? Also, what do the little “P”s stand for? One is bolded and the other is not.
The 'shell' and the two 'P's are marked with red arrows in this diagram:

http://155.178.201.160/d-tpp/1809/05475R30.PDF
I’ve scoured FAA guides trying to locate what it could be, but so far, no luck.
Any help is appreciated!

Somewhere in here perhaps https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/media/editions/cug-complete.pdf

Please add a screenshot unless its forbidden by the copyright holder. Judging by link it may not be there that long! If not a quick MS paint renduring would suffice.

@Bageletas -- it's a FAA/NACO approach plate, so it's a US federal gov't work = no copyright to begin with

What you want is the Frontmatter to the Terminal Procedures Publication, and in particular the pages under "Approach Lighting System" -- these document all the various permutations of visual approach aids found in the US NAS.
As to the symbols you are specifically asking about -- the "shell" is the standard symbol for an ODALS (OmniDirectional Approach Lighting System) that consists of two steady burning lights at each side of the runway threshold and five sequenced flashers leading down the extended runway centerline for 1500'.  The two circled "P"s are also standard symbols, but for PAPI (Precision Approach Path Indicator) lights -- a set of four bicolor (red/white) lights that sit beside the runway and are aimed so that you can see if you're above, on, or below the glidepath based on the combination of red and white lights you see.
As to the symbols being reverse (not boldened)?  That means that those lights are hooked up to a PCL (Pilot Controlled Lighting) box that listens for sequences of microphone clicks on the airport control frequency (UNICOM/CTAF, or tower for a part-time towered airport) and turns on the lights hooked up to it for a set period of time when a suitable sequence is given by a pilot.


text:
Is the turn coordinator showing yaw or roll a mix of the two?
I'm not talking about the ball, but instead the plane symbol shown on the instrument:

Is it showing a roll or is it yaw that it shows? Or is it a mix of the two?
IE, if I do my darndest to fly straight as I bank the wings (uncoordinated flight, so ignore the ball reading), what will I see? If I turn with the rudder, but do my darndest to keep the wings level with ailerons, what will I see?
My interest is trying to understand and gauge (pun intended!) what you can know from this instrument about yaw and or bank if you loose your attitude indicator while in IMC.

Which plane shown, sorry?

We have some other questions on ASE about turn coordinators which you might find helpful (and may have already addressed this question)

@Koyovis I added a picture. The plane symbol shown on the instrument itself.

What you are looking at is a 2 minute standard rate turn gauge.  You roll into the turn and do your darndest  to keep the ball centered (with the rudder).  This will give a turn rate of three degrees per second, or 180 degrees in 60 seconds.  Other experiments can be done in VFR conditions.

Does this question help?

It's a mix of the two because the gyro is canted at angle such that it is sensitive to both roll rate and and yaw rate (note that it's roll rate, not bank angle).
The result is you start to get a turn indication immediately with the bank (a turn and bank has a slight lag because there is no indication until the heading change has started slightly after the bank), and straight yaw indications without bank are reduced from what they would be in a turn and bank.
In an airplane with a regular turn and bank, if you get bumps that make the nose swing back and forth while the wings remain level, the turn indicator needle will swing from side to side because its gyro doesn't know the airplane isn't banked; it just knows that yaw motions are happening.  A turn and bank can be a pain to use in bumpy air in a plane that likes to wag from side to side in turbulence.  You can't really use the indication until the slip/skid ball is settled down and centered.
A turn coordinator with its canted gyro does this a lot less because it's only partially sensitive to yaw rates, and because it's also sensitive to roll rates, it gives you an indication of banking into a turn immediately upon dropping the wing.
The overall result is that initial indication is from the roll into or out of the turn, and once the change of bank has stopped, the indication is coming from the yaw rate of the turn itself.
Being sensitive to roll and yaw rates of motion, to work well, a turn coordinator's gyro needs an internal damper to dampen its motion.  The turn and bank in my old '68 Cessna Cardinal went bad once when the internal damper failed.  The plane symbol would dance around constantly, much worse than a turn and bank needle (which has no damping), making the instrument unusable even though the gyro was still running.

Thanks, very helpful answer. Since you say it is both roll rate and yaw rate, is it true to say it would go back to "level wings" if you hold a turn long enough (and consistently enough)? (If so, couldn't that mean that one of the VFR into IMC illusions could be reinforced instead of dispelled by this instrument?)

Well if you are in a stabilized turn, you have a constant yaw rate and that is being shown as a tilted airplane.  It won't go back to level because there is still a continuous acceleration happening, the lateral change in direction.


text:
What options are there when in a base or final traffic pattern to allow higher priority traffic to take off?
Today, my instructor and I were practicing landings - touch and go's.
We are at an untowered airport, KLGD. Wind was favoring runway 30.
There's been some fires in the area; we checked the NOTAMs and there was no TFR in 50 miles of the airport.
There was 2 single engine air tankers (SEATs) and a larger jet tanker operating out of the airport off the same runway.
Many times, the fire traffic would overfly the field from the NE, join the downwind and we'd turn downwind from base from crosswind a ways behind them. A few times we extended our downwind to about twice as far out to let one take off ahead of us or to give space when they were doing a base and final in front of us.
Once, one of the tankers finished taxing and held short at A2 for 30 about as we turned from base to final (as usual, we did a touch and go).
Another time, a tanker turned downwind behind us and somewhere around turning base another tanker on the ground held short at A2 for 30. We could/would have extended our downwind to let them go, but didn't want to delay the SEAT in the pattern behind us. Shortly after we turned final, the tanker on the ground called the SEAT in the pattern behind us and got permission to go before he landed. We did our touch and go, and then turned crosswind early so they could take off sooner (and fly runway heading, then turn right to the North/East).
We made sure to always call crosswind, downwind, left base, final, "on the go" (touch and go) to try to coordinate with them.
It was good practice - crosswind landings got a lot better today. And we got to practice wake turbulence avoidance each time a 4 engine tanker was in the pattern ahead of us.
I thought the day went well until I talked to the fuel guy at the end of the day. He said some of the tankers were pretty annoyed when they had to hold short for a touch and go. He said maybe I should use runway 35 (which is left traffic like 30). (I'm open to the suggestion, but have concerns about how to keep traffic apart when you have two active runways with overlapping/intersecting patterns). That was the first I heard of it, nothing on the radio seemed to indicate any urgency - every thing was very standard calls of pattern positions. That being said, in my mind a student practicing landings is lower priority than a full fire tanker ready to go when things are burning somewhere.
In a towered airport, if something is higher priority, ATC can make that decision. But at a non-towered airport, there is no one to do that for us; it is up to the pilots to coordinate.
In reviewing the flight lesson and the day in general, my question is: in non-towered scenario, is there any consensus or standard phaseology for coordinating or communicating priority, and second, if I am on base or final, what are my options to allow higher priority traffic that is holding short of the runway to take off ahead of me? What about the "squeezed" scenario where I have priority traffic in the pattern behind me and traffic holding short on the ground?

Related

How would you have done the pattern if the tankers were responding to a fire next to your own house?

If the tankers wanted priority they should have used the radio and asked for it.

Not trying to disparage you here, you did nothing legally wrong, but if you noticed that these fire fighting aircraft were using the airport so heavily, you probably should have found a different airport to use or have done something other than pattern work away from the field. Try to accommodate emergency services as much as possible, a slow aircraft in the pattern while you are trying to refuel and fight for lives and property is really frustrating...

@Sanchises Not arguing about being out of their way (otherwise I wouldn't have bothered to ask the question.) I'm trying to figure out what I can do to be out of their way, especially when one of them is ready after I've turned base.

@Azendale if you were on final and there was traffic behind you and traffic waiting to take off, well, just land and get clear and then stay out of their way.  One time is no big deal; it's being in their way for an extended period.   Or you could just abandon the approach and climb away over the runway, then off toward the upwind side of the airport to get clear. Your instructor really should have just had you depart once and go to another airport under the circumstances, so it's really on the instructor's decision making here. Your instincts sound good though since it made you uncomfortable.

I'm not even convinced you were really "annoying them"... the fuel point person might have seen you practicing T&G's and thought to themselves "why are they doing that when these guys are trying to work" and then when refueling, might have asked a pilot a leading question, or perhaps the pilots might have made an off-hand like "nice to be able to only practice T&Gs" and the fuel attendant took it out of context. If they didn't communicate it to you personally or on the air, then don't worry about it.

If the airport is supporting active, frequent firefighting ops, the single best thing you can do is to go elsewhere and be completely out of their way. I see some terrain in that area, so I don’t know that your CFI would want you going elsewhere if you’re solo, but if dual you might suggest doing a short XC; you’ll need the time and experience anyway.
If you can’t leave the pattern due to weather, or the firefighting ops aren’t that frequent, you can modify your pattern to give them priority. I often do this to make things easier for any transient traffic.
On the departure leg, turn crosswind earlier—as soon as terrain and obstacles permit, rather than the usual 700 AGL. This will allow faster aircraft behind you to depart sooner.
On the downwind leg, look for aircraft taxiing toward the runway, and before turning base, offer to extend your downwind (or do 360s) so they can depart immediately. The key here is to be aware of what’s going on before you turn base.
You can also tell priority traffic behind you in the pattern that you’ll extend your downwind so they can turn base immediately. This is tricky if you can’t see them to decide when to turn base yourself, but your CFI should be able to figure something out.
Once on base or final, it gets more dangerous (and less effective) to try to adjust your spacing to let someone else out before you. Your CFI will know some tricks, and if needed you can give him the controls to execute them. For now, work on having enough situational awareness that you don’t need them.
Note that adjustments to any leg of your pattern will make it inconsistent, which may be good or bad for you depending on the stage of your training. Early on, you want to keep things as consistent as possible while you learn the mechanics. But later, it helps to vary things so you learn how to apply those mechanics to the weird situations you’ll find yourself in from time to time. For instance, I still struggle a bit with when to reduce power, add flaps, run checklists, etc. when ATC tells me to enter on a base or straight-in because I was taught to do those things at specific points starting on downwind.


text:
Are the VFR weather minimums in 91.155(d) redundant because of 91.155(a)?
14 CFR 91.155(d) specifies that:

... no person may take off or land an aircraft, or enter the traffic pattern of an airport, under VFR, within the lateral boundaries of the surface areas of Class B, Class C, Class D, or Class E airspace designated for an airport ... unless ground visibility at that airport is at least 3 statute miles ...

But we already know from the table in 91.155 (a) that for Class B, C, D, and E, the minimum flight visibility is 3 sm. So it's not possible for this rule (d) to apply without already triggering the rule (a).
My question is then what's the point of this additional rule? Am I misinterpreting the text?

Short answer: pilots need flight visibility, ATC needs ground visibility.

There are two different definitions of visibility in the regulations you mentioned: flight visibility and ground visibility. They're defined in 14 CFR 1.1:

Flight visibility means the average forward horizontal distance, from the cockpit of an aircraft in flight, at which prominent
  unlighted objects may be seen and identified by day and prominent
  lighted objects may be seen and identified by night.
Ground visibility means prevailing horizontal visibility near the earth's surface as reported by the United States National Weather
  Service or an accredited observer.

The practical difference is that only pilots can determine flight visibility; ATC and/or ground stations (AWOS/ASOS) determine ground visibility. The regulations aren't redundant because they're talking about different things and also about different needs:

91.155(a) applies to all airspace. At 5000' (or whatever), only flight visibility makes sense to determine if conditions are VFR.
91.155(d) applies to terminal (airport) airspace. That means ATC is also very interested in whether conditions are VFR or not, and they can only work with ground visibility.

Note that the full text of 91.155(d) also covers the case of uncontrolled airports with no weather reporting (emphasis mine):

(d) Except as provided in §91.157 of this part, no person may take off
  or land an aircraft, or enter the traffic pattern of an airport, under
  VFR, within the lateral boundaries of the surface areas of Class B,
  Class C, Class D, or Class E airspace designated for an airport—
(1) Unless ground visibility at that airport is at least 3 statute
  miles; or
(2) If ground visibility is not reported at that airport, unless
  flight visibility during landing or takeoff, or while operating in the
  traffic pattern is at least 3 statute miles.

A more complete quoting of 14 CFR 91.155 as it pertains to this question would be:

(d) Except as provided in § 91.157 of this part, no person may take off or land an aircraft, or enter the traffic pattern of an airport, under VFR, within the lateral boundaries of the surface areas of Class B, Class C, Class D, or Class E airspace designated for an airport -
(1) Unless ground visibility at that airport is at least 3 statute miles; or
(2) If ground visibility is not reported at that airport, unless flight visibility during landing or takeoff, or while operating in the traffic pattern is at least 3 statute miles.

There are not two rules in effect, there is only one rule concerning the visibility requirements in class B, C, D & E airspace - Three statute miles.  This rule is mentioned in the text, and shown in the table.  It can be either reported ground visibility, or flight visibility.
This rule's mention in one place does not cancel out or "trigger" another rule, you simply use the information available to comply.  There is no conflict if you read the entire section in context.


text:
What educational qualifications are required to become a pilot in the UK?
In order to obtain a pilot's licence in the UK, are any formal educational qualifications (such as school-leaving certificates) required?
As well as any statutory or other formal requirements, do employers of commercial pilots typically require any education qualifications? Or is holding a pilot's licence generally all that is needed?
In the absence of relevant educational qualifications, are there other skills, capacities or demonstrable advantages that would help someone who lacked them, but still hoped to become a pilot?

Do you mean just getting a private pilot's license, or becoming an airline pilot?

There's no GCSE or A-Level requirements for a pilot but you will have to pass a number of theory exams.  The usual path is PPL (private pilot's licence), CPL (commercial pilot's licence) and ATPL (Airline Transport Pilot's Licence).  You can get your PPL at age 17.  See here:  https://www.caa.co.uk/General-aviation/Pilot-licences/EASA-requirements/PPL-SPL-BPL/Common-requirements-for-the-PPL,-SPL-and-BPL/

If you are looking to fly for airlines there are two methods of getting your ATPL, modular and integrated courses: https://www.pilotcareernews.com/pilot-training-integrated-vs-modular/  I've seen prices around £40k for modular to over £80k for integrated though these both seem a little low

nice edit, Daniele Procida!

As has been pointed out, there are requirements, but being fluent in the language is not one of them. Proficient is the requirement, with emphasis on aviation requirements. Other than that, and the obvious pilot training requirements, there are no formal education requirements for a pilot license. If you want to get a job as a pilot, the employer may have other requirements you must meet.

There are no formal education requirements. However you must be fluent in English. The details can be found here https://www.caa.co.uk/General-aviation/Pilot-licences/EASA-requirements/PPL-SPL-BPL/Common-requirements-for-the-PPL,-SPL-and-BPL/

Welcome to Aviation! Whilst this may theoretically answer the question, it would be preferable to include the essential parts of the answer here, and provide the link for reference.

Commercial aviation I am interested in.

You don't have to be fluent in English. You have to pass a language proficiency test.


text:
Do you have to worry about airborne disease on an international air flight?
Flu? Pneumonia? Anthrax? smallpox? Do you have to worry about them or there are designs in place to prevent them? Like some sort of sophisticated ventilation system?
Models to work with: Most common ones: Boeing 737, Airbus A320

Do you have to worry? Not really.  Although the there are no filtering systems to catch pathogens it's not appreciably different from other modes of shared transportation like buses and trains.

I'm afraid you're probably not going to like the answer! And really, the model makes little or no difference.
The MITRE Corporation did some studies on this and a good summary can be found in the article
Detecting Aircraft Pathogens Before It's Too Late
The summary points are

the researchers determined that most particles stayed suspended in the aisle, so when booking a trip, take a window seat

and

Particles also did not travel far outside the contaminated row, and if they did, it was across the row. Previously, it was thought that contaminants would travel front to back, or back to front.

Most worryingly:

The need for such sensors was evident in the 2003 outbreak of Severe Acute Respiratory Syndrome (SARS), which originated in an Air China flight from Hong Kong to Beijing, spread through 18 countries, and resulted in 774 fatalities. Asian economies suffered $11 billion in damages

As for controlling pathogens on board an aircraft, the CDC provide guidance which involves the same procedures you'd use on the ground (Hand washing, PPE, handling of bodily fluids).
Although air is no doubt filtered, as far as I know there is nothing special about the filters used on Aircraft that would be unique to aviation, nor offer any additional defense against airborne pathogens.

Wow so this is basically another "since it makes little economic sense, we ain't gonna go that extra mile" stuff?

No, not more than about catching a bug at any populated and air conditioned space. Some of the air in the cockpit is recirculated and before it re-enters the cockpit, it is filtered through HEPA filters. From this document:

The vast majority of U.S. airliners use high-efficiency particulate air (HEPA) recirculation filters for cabin air, and these filters are highly effective at collection of solid and liquid particulates.

These filters can remove 99.97% of particles up to 0.3 µm, as defined by MIL-STD-282 Method 102.9.1. Bacterial and viral particles are smaller, but the size of 0.3 µm is chosen because it is the hardest one to filter, smaller particles are caught in the HEPAs with a high rate (up to 98%) as well. In hospitals the filters are used together with strong ultraviolet light to kill the bacteria could by the filters.
Notice that the document above mentions that most US airlines use HEPA, which implies that filtering practices are airline dependent and not prescribed by FAA. The advise seems to be: fly a reputable airline.
Do you have to worry about bacteria and viruses on board of aircraft? If you're truly worried, wear a mask:

Though it’s inconclusive whether masks can block airborne viruses, “one thing we learned from the literature that we looked at is that if the healthy person is wearing a mask and walks into a sickroom and touches infected surfaces, the mask makes it hard to touch his or her own nose and mouth,” says Finkelstein, who is also an associate professor at Harvard Medical School.

I doubt most of the masks you see people wearing about are actually HEPA masks, and none of the one's I've ever seen are sealed around the mouth and nose well enough to keep anything bacterial sized out. They will keep you from directly touching your face, so they should slow the progress of anything you may have on your hand. Not attacking your answer, just providing something to think about.

@FreeMan Yes there is nothing that can provicde a 100% guarantee of not catching a contagious bug. We can only reduce the chance, and if a mask helps by any mechanism than it may be worthwhile to wear one.

A mask - that is perfectly logical, but not that reasonable. Some international flights take up to 22 hours - it's simply impossible to wear a mask for that long.

Yes. Some flights (perhaps more) only take 4 hours though. Nobody can give you a method that guarantees 100% of success in 100% of circumstances.


text:
Does an increase in inlet temperature affect fuel flow and power output?
The fuel flow rate decreases as the inlet temperature of the air entering the engine increases. Will the engine produce same amount of power as when the fuel flow was higher?

Are you sure the fuel flow rate always decreases as the inlet temperature increases, and why? PS. Is this from a quiz, and which one?

Most civil aircraft engines are "flat rated". See What is a flat rated engine?

That means, the thrust (power) produced is constant (flat), as ambient temperature increase, up to a certain temperature, and then the turbine inlet temperature limit is reached, and fuel flow and thrust is reduced as the ambient temperature continues to increase.
So, thrust is initially constant as inlet temperature increases, then decreases. It's a bit harder to predict what fuel flow will need to do to achieve this behaviour. It will certainly reduce in the temperature range where thrust is reducing, but in the cooler temperatures before that, it is probably increasing to keep thrust constant. As the chart shows, in this region EGT and N1 rpm are increasing. I expect fuel flow is probably showing the same behaviour as N1.
Thrust cannot actually be measured in flight, so most engines use either N1 rpm, or engine pressure ratio, (turbine exit perssure/engine inlet pressure) as a way to predict thrust. GE typically uses N1, whereas Pratt & Whitney and Rolls Royce usually use EPR. Using EPR is technically better, beacuse it will account for engine deterioration, where as using N1 assumes the fan mass flow remains the same for a given rpm as the engine degrades. But EPR requires 2 pressure measurements, which are less reliable, so most engines that use EPR have N1 control as a backup mode.  See
What is the difference between EPR and rotor speed as thrust setting parameter?


text:
How long is a clearance void time valid?
You're picking up your IFR clearance on the ground and you get a 10 minute void time from now.
What phase of flight is that 10 minute void time clearance good until?
..your wheels are up?
..a certain altitude?
..on course?
..your initial call to ATC?
..or is it from when ATC gives your position report and says "radar contact"?

I added the FAA tag because your previous questions have been about the US. When you ask about regulations or procedures, please always tell us which country you're asking about, because they're different around the world. If you're actually asking about some other country, please just re-tag the question as necessary.

Since you didn't state jurisdiction, I'm assuming US.
From the AIM:

1. Clearance Void Times. A pilot may receive a clearance, when operating from an airport without a control tower, which contains a
  provision for the clearance to be void if not airborne by a specific
  time. A pilot who does not depart prior to the clearance void time
  must advise ATC as soon as possible of their intentions. ATC will
  normally advise the pilot of the time allotted to notify ATC that the
  aircraft did not depart prior to the clearance void time. This time
  cannot exceed 30 minutes. Failure of an aircraft to contact ATC within
  30 minutes after the clearance void time will result in the aircraft
  being considered overdue and search and rescue procedures initiated.

The requirement is to be airborne prior to the clearance void time. You need to contact ATC within 30 minutes of the void time either in the air or to notify them that you did not depart.

The answer is actually in the wording of the clearance itself. This is from the FAA's ATC orders, section 4-3-4:

PHRASEOLOGY−
  CLEARANCE VOID IF NOT OFF BY (clearance void time)

You must be "off", i.e. airborne, by the void time. See also the definition in the P/CG:

CLEARANCE VOID IF NOT OFF BY (TIME)−
  Used by ATC to advise an aircraft that the departure clearance is automatically canceled if
  takeoff is not made prior to a specified time. The pilot must obtain a
  new clearance or cancel his/her IFR flight plan if not off by the
  specified time.

That would be contact after takeoff. The 10 minutes is your interval to get yourself into the controller's airspace and report yourself as such.


text:
Are the student solo endorsements a “package deal” with that one specific instructor?
If someone receives a student who’s completed his old instructor’s pre written solo exam and received an endorsement, do I need to give him my solo test and endorsement?
Or go ahead and complete the flight training/proficiency and 90 day endorsement?
My understanding is that it’s a "package deal", one instructor must do it all. Except the XC pre-flight planning preparation endorsement, and this one can be given by any instructor.
Can someone confirm this? With possible quotes from FAR, ACs or interpretations.

and how would that work with flying schools employing multiple instructors, where a student can receive training from any of them? Sound more like you're looking for an excuse to tag a student with additional cost (to your personal benefit) than anything else. If you don't trust whether the endorsement is valid, that's a reason to investigate. Call the instructor who supposedly issued it for example.

I was in a similar situation as a student a couple weeks ago. My new instructor just wrote a new endorsement without having me take another pre-solo test.

The FAR's don't talk about whether or not a CFI can accept another instructor's solo endorsement. If the student has the endorsement, the 90 day period has not expired, and the make and model of the aircraft in the endorsement matches, then the student is technically good to go.
That said, a good CFI would carefully review the student's log book and, if necessary, require additional instruction/review before allowing the flight school to rent the student an aircraft. The relevant FAR is 61.87.

I concur. I’ve had students who have solo endorsements from a different instructor, and in need of more solo time. As long as those endorsements are correct and valid (the 90-day one), I’m not required to give any additional endorsements (except for each Solo XC). Once the 90-day period is over, I simply have to give a new 90-day endorsement.

61.195 Flight instructor limitations and qualifications
(d) Limitations on endorsements. A flight instructor may not endorse a:
(1) Student pilot's logbook for solo flight privileges, unless that flight instructor has -
(i)Given that student the flight training required for solo flight privileges required by this port; and
(ii) Determined the student is prepared to conduct the flight safely under known circumstances, subject to any limitations listed in the student's logbook that the instructor considers necessary for the safety of the flight.


text:
Why is an air intake located on the root of the tail on some aircraft?
There is a small air intake on the root of the tail of some aircraft, especially those with engines near the end of the aircraft. What is it and why is it located there?

If you put your hand next to one of the rectangular exhaust louvers below and behind the engines, you will find the air coming out is quite hot.  Those are the exhaust end of the inlet on the fin.  The heat is what was extracted from the bleed air that was going though the AC packs.

That is the Ram Air Inlet for the air conditioning system:

Ram air, taken from the air scoop in the base of the vertical fin, is used as the cooling medium for  the  heat  exchangers.  Ram  air  passes  across  the  precooler  and  the  dual  heat  exchangers, extracting heat from the bleed air used by the air-conditioning packs. The ram air is discharged through exhaust louvers on the upper left and right sides of the aft fuselage.

During unpressurized flight, ram air may be used to ventilate the cockpit and cabin.

(Bombardier Challenger 605 - Air Conditioning & Pressurization)
The reason why it is located there is obvious from the picture above: the two air conditioning units (ACUs) are located just below so this provides the shortest duct. For tail mounted engines, this is the optimal location for the ACUs (also called PACKs) because the bleed air ducts from the engines (or APU) can be short this way. The ram air can also be used for ventilation when the pressurization has failed.
For wing mounted engines, the PACKs are usually located in the belly. The inlets are then found on the underside of the aircraft:
What exactly are those openings in the bellies of many jetliners?
On some turboprops you can also find them on the side:
What's this hole on the ATR-72?

You should mention that the same inlet does double duty.  It is also the source of ram air flow for emergency cabin ventilation when flying depressurized.

@JohnK Good point, added.


text:
Is this new intake of Airbus and Boeing aircraft's NACA inlet?
Anybody knows the name of this intake? look at the bellow images:

Why don't Airbus and Boeing use the conventional NACA inlet? Why did they invent this kind of intake? I can see some parts of these aircraft that the conventional NACA inlet are embodied in.

Those inlets don't require the NACA duct profile because the openings are presented toward the airflow, being on a sloping surface relative to the freestream.  The NACA profile in those locations serves no useful purpose and is a probably less effective, if anything.
The NACA duct profile was developed for inlets on surfaces that are completely parallel to the airflow, like along the straight sides of a fuselage or nacelle, where the freestream flow just passes on by (like a static port you might say).  They were developed as a low drag alternative to the traditional scoop projecting into the airstream that you would normally have to use in such a location.
The sides of the NACA Profile, induce a change in direction of the ram air free stream without any projections (it's thought that the sides of the ramp act like vortex generators and it's the vortices that "pull" the free stream down the ramp) so that ram air is drawn down the ramp to the inlet opening.  On a sloping surface like a wing root fairing as in those pictures, the ram air is directly impinging on the opening (as if it was a scoop sticking out) and doesn't need any "airflow redirection tricks" like the curved sides on the NACA inlet ramp.

This answer says that it is the ram air inlet for the cabin air conditioning. My take is that they've changed the design from the NACA duct to make it open and close on demand. It is harder to make a variable NACA duct due to the curvatures involved.

Interesting! because in that answer the LH RAI is a conventional NACA duct but in new versions of A380 that I have posted its images in my question, the LH RAI intake is changed.